U.S. patent application number 14/268012 was filed with the patent office on 2014-11-06 for dual ring configuration for a stationary seal.
This patent application is currently assigned to EcoMotors, Inc.. The applicant listed for this patent is EcoMotors, Inc.. Invention is credited to Diana Brehob, Peter Hofbauer.
Application Number | 20140326131 14/268012 |
Document ID | / |
Family ID | 51840723 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140326131 |
Kind Code |
A1 |
Hofbauer; Peter ; et
al. |
November 6, 2014 |
Dual Ring Configuration for a Stationary Seal
Abstract
In a piston-ported engine, a sealing ring may be placed in a
groove in the cylinder. As the groove is of greater diameter than
the cylinder, the sealing ring overlaps into a helix allowing it to
be enter the cylinder. However, such a helix does not fit into a
groove without when in the helix. Alternatively, a shorter sealing
ring is placed into the groove. However, the gap is too large.
According to one embodiment, a groove of double the width of the
ring is provided and the helical ring is installed and caused to
unwind in the groove so that the ring sits in a plane. A spacer
ring is placed in the groove to fill the extra space in the groove.
An elastomeric material or a tension spring in an outer groove in
the sealing ring can be used to cause the ring to press against the
piston.
Inventors: |
Hofbauer; Peter; (West
Bloomfield, MI) ; Brehob; Diana; (Dearborn,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EcoMotors, Inc. |
Allen Park |
MI |
US |
|
|
Assignee: |
EcoMotors, Inc.
Allen Park
MI
|
Family ID: |
51840723 |
Appl. No.: |
14/268012 |
Filed: |
May 2, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61818933 |
May 3, 2013 |
|
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Current U.S.
Class: |
92/172 ; 277/434;
277/472; 29/888.044 |
Current CPC
Class: |
Y10T 29/49256 20150115;
F16J 9/14 20130101; F16J 10/02 20130101 |
Class at
Publication: |
92/172 ; 277/434;
277/472; 29/888.044 |
International
Class: |
F16J 9/12 20060101
F16J009/12; F16J 9/06 20060101 F16J009/06 |
Claims
1. A piston and cylinder assembly, comprising: a cylinder having an
annular cylinder groove defined in the inner surface of the
cylinder; a sealing ring installed in the cylinder groove wherein
ends of the sealing ring are caused to overlap to allow the sealing
ring to enter the cylinder and when the sealing ring is placed in
the cylinder groove, ends of the sealing ring are proximate each
other; and a spacer ring installed in the cylinder groove wherein
ends of the spacer ring are proximate each other when the spacer
ring is contracted to enter the cylinder and when the spacer ring
expands in the cylinder groove, ends of the spacer ring are
separated by a gap.
2. The assembly of claim 1, further comprising: a piston installed
in the cylinder proximate the groove wherein the piston is adapted
to reciprocate within the cylinder.
3. The assembly of claim 1 wherein a height of the sealing ring and
a height of the spacer ring are a predetermined height and a height
of the groove is not less than the sum of predetermined heights of
the sealing ring and the height of the spacer ring.
4. The assembly of claim 1 wherein the sealing ring forms a helix
when the ends of the sealing ring overlap.
5. The assembly of claim 1, further comprising: a piston disposed
in the cylinder with the sealing ring and the spacer ring
encircling the piston; and a compression ring installed into an
annular groove in the piston.
6. The assembly of claim 5 wherein when the sealing ring is
encircling the piston, the ends of the sealing ring are separated
by a sealing ring gap and the sealing ring gap is significantly
smaller than the gap in the spacer ring.
7. The assembly of claim 1 wherein the sealing ring has a
substantially rectangular cross section with a groove defined in an
outer surface of the sealing ring, the assembly further comprising:
an elastomeric seal disposed in the groove in the sealing ring.
8. The assembly of claim 1 wherein the sealing ring has a
substantially rectangular cross section with a groove defined in an
outer surface of the sealing ring, the assembly further comprising:
a tension spring disposed in the groove in the sealing ring.
9. A piston and cylinder assembly, comprising: a cylinder having an
annular groove defined in the inner surface of the cylinder; a
sealing ring installed in the annular groove; and a spacer ring
installed in the annular groove wherein the sealing ring is
installed prior to installation of the spacer ring.
10. The assembly of claim 9 wherein: ends of the sealing ring are
caused to overlap to allow the sealing ring to form a helix to
enter the cylinder; when the sealing ring is placed in the groove,
ends of the sealing ring are proximate each other; ends of the
spacer ring are proximate each other when the spacer ring enters
the cylinder; and when the spacer ring expands in the groove, ends
of the spacer ring are separated by a gap.
11. The assembly of claim 10 wherein the sealing ring has an
annular groove formed in an outer surface of the sealing ring, the
assembly further comprising: one of a tension spring and a
deformable material placed in the annular groove in the sealing
ring prior to installing the sealing ring in the groove in the
cylinder.
12. The assembly of claim 9 wherein: the sealing ring is placed
into a helical shape with a diameter less than a diameter of the
cylinder to allow insertion of the sealing ring into the cylinder;
when the sealing ring is inserted into the groove, it is pressed
outwardly to cause the sealing ring to lie in a plane; the spacer
ring is placed into a spiral shape with the ends of the ring
overlapping to allow insertion of the sealing ring into the
cylinder; and the spacer ring is pressed outwardly with the ends no
longer overlapping when pressed into the groove.
13. The assembly of claim 12 wherein the spacer ring has a chamfer
on one end of the ring to allow the two ends to move past each
other when the spacer ring is pressed into the groove.
14. The assembly of claim 12 wherein each of the sealing ring and
the spacer ring have at least one groove on an outer surface with a
tension spring disposed therein.
15. A method to install rings in an annular groove defined in the
inner surface of a cylinder, comprising: causing a sealing ring to
form a helix such that ends of the sealing ring overlap; placing
the sealing ring in the helix configuration into the cylinder;
expanding the sealing ring in the groove such that the ends of the
sealing ring no longer overlap; and placing a spacer in the groove
in the cylinder.
16. The method of claim 15 wherein the spacer is a spacer ring and
placing a spacer in the groove in the cylinder comprises:
compressing a spacer ring such that the ends of the spacer ring are
proximate each other; placing the spacer ring in the cylinder; and
expanding the spacer ring in the groove adjacent the sealing
ring.
17. The method of claim 16 wherein the expanding the sealing ring
in the groove in the cylinder is performed with the use of a
fixture to cause the sealing ring to expand outwardly into the
groove in the cylinder.
18. The method of claim 16 wherein the fixture includes a portion
of a cone.
19. The method of claim 16 wherein the sealing ring has an annular
groove defined in an outer surface of the sealing ring, the method
further comprising: placing a deformable seal into the groove in
the cylinder prior to placing the sealing ring into the
cylinder.
20. The method of claim 16 wherein the sealing ring has an annular
groove defined in an outer surface of the sealing ring, the method
further comprising: placing a tension spring into the groove in the
cylinder prior to placing the sealing ring into the cylinder.
Description
FIELD
[0001] The present disclosure relates to a ring arrangement for a
stationary seal associated with a reciprocating component.
BACKGROUND
[0002] Rings are used to seal between a reciprocating piston and a
cylinder. Conventionally, the rings are placed in grooves in the
piston. In FIG. 1, a piston 100 is shown viewed from the top.
Piston 100 has a piston skirt extending downwardly from the piston
top. The piston skirt is generally cylindrical and has grooves
formed in the outer surface. The inward edge of the groove is shown
as a dashed circle 102. A piston ring 104 is shown that is spread
apart to form a gap 106.
[0003] The situation when piston ring 104 is allowed to contract
into the groove in piston 100 and into the cylinder (not shown) is
shown in FIG. 2. Gap 106 is much smaller in the configuration in
FIG. 2 than in the expanded position shown in FIG. 1. It is
advantageous that gap 106 is very small when ring 104 is installed
into the cylinder (not shown) so that a minimal amount of gases can
pass through gap 106.
[0004] In a two-stroke engine, it is undesirable to lose oil
through the ports both from an oil consumption and emissions
perspective. Thus, two-stroke engines are provided with an oil ring
that is located either in the lower portion of the piston i.e.,
below the ports or in the cylinder wall below the ports at TDC. A
disadvantage of having the oil ring in the piston is that the
engine is longer in the direction along the cylinder liner axis. In
an OPOC engine, such as disclosed in U.S. Pat. No. 6,170,443, which
is incorporated herein in its entirety, the extra length is in the
longest dimension of the engine. A stationary seal can be a
challenge to install the seal with a small gap in the cylinder
liner.
[0005] An example of an OPOC engine 10 is shown in FIG. 27. An
inner piston 12 and an outer piston 14 are associated with a right
cylinder (not shown to view the pistons) and an inner piston 13 and
an outer piston 15 are associated with a left cylinder (not shown).
Pistons 12 and 13 couple to crankshaft 20 via pushrods 16 and
pistons 14 and 15 coupled to crankshaft 20 via pullrods 18 (a pair
of pullrods 18 for each outer piston). Inner pistons 12 and 13 have
a groove near the bottom of the piston. In contrast, outer pistons
14 and 15 have only grooves for compression rings and no groove to
accommodate an oil sealing ring. The oil sealing rings are disposed
in grooves in the cylinder liners, not shown in FIG. 27.
[0006] A sealing ring, which may serve as a stationary oil ring
mounted into the cylinder liner, is shown in FIGS. 3 and 4. A
cylinder 120 has a groove formed in an inner surface of cylinder
120. The base of the groove is shown as a dashed circle 122 (hidden
line in the view shown in FIG. 3). A ring 124 with a small gap 126
is shown inside cylinder 120. When ring 124 is expanded to fit
inside the groove in cylinder 120, gap 126 becomes intolerably
large. That is, the gas flow through gap 126 would be too
great.
[0007] In one alternative of a stationary seal, the cylinder is
formed in two parts which couple axially. The groove is located at
the end of one cylinder part. The ring is installed into the groove
before the two parts of the cylinder are assembled. Disadvantages
of this configuration include: higher part count: 2 pieces plus
bolts for assembly; extra material to accommodate the bolts; and
the requirement that the two pieces be perfectly aligned during
machining and final assembly to provide a completely collinear
cylinder liner in which the piston may freely reciprocate.
[0008] It would be desirable to have a ring that could be installed
in groove in a single-piece cylinder, but without a large gap.
SUMMARY
[0009] To overcome at least one problem in the prior art, a piston
and cylinder assembly is disclosed that has: a cylinder having an
annular cylinder groove defined in the inner surface of the
cylinder, a sealing ring installed in the cylinder groove wherein
ends of the sealing ring are caused to overlap to allow the sealing
ring to enter the cylinder and when the sealing ring is placed in
the cylinder groove, ends of the sealing ring are proximate each
other, and a spacer ring installed in the cylinder groove. Ends of
the spacer ring are proximate each other when the spacer ring is
contracted to enter the cylinder and when the spacer ring expands
in the cylinder groove, ends of the spacer ring are separated by a
gap.
[0010] The assembly further includes a piston installed in the
cylinder proximate the groove wherein the piston is adapted to
reciprocate within the cylinder. The sealing ring and the spacer
ring encircling the piston and a compression ring installed into an
annular groove in the piston.
[0011] A height of the sealing ring and a height of the spacer ring
are a predetermined height and a height of the groove is not less
than twice the predetermined height and substantially equal to
twice the predetermined height. The sealing ring forms a helix when
the ends of the sealing ring overlap.
[0012] When the sealing ring is encircling the piston, the ends of
the sealing ring are separated by a gap and the gap in the sealing
ring is significantly smaller than the gap in the spacer ring.
[0013] The sealing ring has a substantially rectangular cross
section with a groove defined in an outer surface of the sealing
ring. Some embodiments include an elastomeric seal disposed in the
groove in the sealing ring and in other embodiments a tension
spring.
[0014] Also disclosed is a piston-and-cylinder assembly that
includes a cylinder having an annular groove defined in the inner
surface of the cylinder, a sealing ring installed in the annular
groove, and a spacer ring installed in the annular groove wherein
the sealing ring is installed prior to installation of the spacer
ring.
[0015] Ends of the sealing ring are caused to overlap to allow the
sealing ring to form a helix to enter the cylinder. When the
sealing ring is placed in the groove, ends of the sealing ring are
proximate each other. Ends of the spacer ring are proximate each
other when the spacer ring enters the cylinder. When the spacer
ring expands in the groove, ends of the spacer ring are separated
by a gap.
[0016] The sealing ring has an annular groove formed in an outer
surface of the sealing ring. The assembly may further include one
of a tension spring and a deformable material placed in the annular
groove in the sealing ring prior to installing the sealing ring in
the groove in the cylinder.
[0017] The sealing ring is placed into a helical shape with a
diameter less than a diameter of the cylinder to allow insertion of
the sealing ring into the cylinder. When the sealing ring is
inserted into the groove, it is pressed outwardly to cause the
sealing ring to lie in a plane. The spacer ring is placed into a
spiral shape with the ends of the ring overlapping to allow
insertion of the sealing ring into the cylinder. The spacer ring is
pressed outwardly with the ends no longer overlapping when pressed
into the groove.
[0018] The space ring has a chamfer on one end of the ring to allow
the two ends to move past each other when the spacer ring it
pressed into the groove. Each of the sealing ring and the spacer
ring has at least one groove on an outer surface with a tension
spring disposed therein.
[0019] Also disclosed is a method to install rings in an annular
groove defined in the inner surface of a cylinder, including:
causing a sealing ring to form a helix such that ends of the
sealing ring overlap, placing the sealing ring in the helix
configuration into the cylinder, expanding the sealing ring in the
groove such that the ends of the sealing ring no longer overlap,
and placing a spacer ring in the groove in the cylinder. The spacer
can be a spacer ring. Placing a spacer in the groove in the
cylinder includes: compressing a spacer ring such that the ends of
the spacer ring are proximate each other, placing the spacer ring
in the cylinder, and expanding the spacer ring in the groove
adjacent the sealing ring. The expanding the sealing ring in the
groove in the cylinder is performed with the use of a fixture to
cause the sealing ring to expand outwardly into the groove in the
cylinder.
[0020] The fixture includes a portion of a cone.
[0021] The sealing ring has an annular groove defined in an outer
surface of the sealing ring. The method also includes: placing a
deformable seal into the groove in the cylinder prior to placing
the sealing ring into the cylinder.
[0022] The sealing ring has an annular groove defined in an outer
surface of the sealing ring. A tension spring is placed into the
groove in the cylinder prior to placing the sealing ring into the
cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIGS. 1 and 2 are illustrations of a top view of a piston
with an external groove and a piston ring with the ring expanded
and contracted, respectively;
[0024] FIGS. 3 and 4 are illustrations of a top view of a cylinder
with an internal groove and a ring, with the ring contracted, and
expanded, respectively;
[0025] FIG. 5 is an illustration of a top view of a cylinder with
an internal groove and a ring inside the cylinder with the ring
compressed such that the ends overlap;
[0026] FIG. 6 is a side view of the ring of FIG. 5 with the ends
overlapping;
[0027] FIG. 7 is a portion of a cylinder in cross section showing
an overlapping ring in a groove in the cylinder;
[0028] FIG. 8 is an illustration of a top view of a cylinder with
an internal groove and a ring installed in the groove;
[0029] FIG. 9 is a side view of the ring of FIG. 8;
[0030] FIG. 10 is a portion of a cylinder in cross section showing
a ring installed in the groove;
[0031] FIG. 11 is a portion of a cylinder in cross section showing
two rings installed in the groove;
[0032] FIG. 12 is an illustration of a sealing ring with a tension
spring installed in an outer groove of the sealing ring;
[0033] FIG. 13 is an illustration of a portion of a cylinder and
piston with a stationary ring in a groove in the cylinder;
[0034] FIGS. 14 and 15 illustrate procedures by which stationary
rings are installed in the groove in the cylinder;
[0035] FIG. 16 is an illustration of the sealing ring and a tension
spring when ends of the sealing ring overlap according to an
embodiment of the disclosure;
[0036] FIGS. 17-24 are illustrations of an installation dual rings
in a groove in unitary cylinder liner;
[0037] FIG. 25 is an illustration of a two portions of a spacer
ring with a portion of a tension spring in a groove in the spacer
ring;
[0038] FIG. 26 is an illustration of a cylinder liner having a
sealing ring and a spacer ring disposed in a groove in the cylinder
liner; and
[0039] FIG. 27 is an isometric representation of a drive train of
an OPOC engine.
DETAILED DESCRIPTION
[0040] As those of ordinary skill in the art will understand,
various features of the embodiments illustrated and described with
reference to any one of the Figures may be combined with features
illustrated in one or more other Figures to produce alternative
embodiments that are not explicitly illustrated or described. The
combinations of features illustrated provide representative
embodiments for typical applications. However, various combinations
and modifications of the features consistent with the teachings of
the present disclosure may be desired for particular applications
or implementations. Those of ordinary skill in the art may
recognize similar applications or implementations whether or not
explicitly described or illustrated.
[0041] In FIG. 5, a top view of a cylinder 140 is shown. Cylinder
140 has a groove in the inner surface 141 of cylinder 140. The base
of the groove is indicated by dashed circle 142. Also shown is a
ring 144, which has been compressed so that the two ends overlap in
region 146. Ring 144 is shown in a side view in FIG. 6 with overlap
region 146. Ring 146 forms a helix and cannot be fit in a groove
that is the height of ring 146. Instead, the groove into which ring
146 can fit when in the configuration shown in FIG. 6 is about
double the height of ring 146. This is shown in FIG. 7 in which a
portion of cylinder 140 is illustrated in cross section. Cylinder
140 has an outer surface 139 and an inner surface 141. A groove is
formed in inner surface 141. When ring 144 is compressed, it
overlaps. The region of overlap is shown in FIG. 7, i.e., showing
two ends of ring 144 in cross section.
[0042] In FIG. 8, ring 144 is caused to expand into the groove of
cylinder 140. There is no overlap when ring 144 expands and instead
a small gap 148 forms. Ring 144 of FIG. 8 is shown in a side view
in FIG. 9 with gap 148. When the ends of ring 144 no longer
overlap, such as shown in FIG. 10, ring 144 takes up only about
half the height of groove 145. In such a configuration, if a piston
were reciprocating with respect to cylinder 140, ring 144 would be
shoved up and down in groove 145, which would compromise its
sealing capability and would readily damage ring 144.
[0043] In FIG. 11, a spacer ring 150 is added to the sealing system
to take up the space in the groove of cylinder 140. Spacer ring 150
need not provide sealing. Thus, it can be a ring such as shown in
FIG. 4 which has a large gap to facilitate its installation into
groove 145 after ring 144 has previously been installed. The
purpose of spacer ring 150 is to fill the extra space in groove 145
in FIG. 10 to allow ring 144 to properly seat in the groove to
provide the desired sealing.
[0044] It is desirable for sealing ring 144, such as is shown in
FIG. 10, to press against the piston (not shown) to scrape excess
oil off the piston as the piston reciprocates in the cylinder. On
the back side of ring 144, a groove 149 is provided, as shown in
FIGS. 7, 10, and 11. The rings described heretofore are split
rings, i.e, having a gap. In one embodiment shown in FIG. 12, a
tension spring 160 that is a continuous ring without a gap, is
placed in the groove in the piston ring (groove 149 in FIGS. 7, 10,
and 11). Groove 149 is not separately visible in FIG. 12; however,
the depth of groove 149 is illustrated as dotted circle 158 in FIG.
12. Sealing ring 144 has an inner surface 156 that rides on the
piston (not shown) and an outer surface 154 that sits within the
groove in the cylinder liner, (groove 145 of FIG. 10). Tension
spring 160 has a size and tension to provide the desired force to
press surface 156 of ring 144 against the piston. A method by which
such a configuration can be installed in the cylinder is discussed
below.
[0045] Referring now to FIG. 13, an alternative embodiment is shown
in which an elastomeric, deformable seal 162 is placed in groove
149 (not separately called out in FIG. 13 because groove 149 is
substantially filled by seal 162). When seal 162 is compressed into
the groove in the ring, ring 144 is pressed against piston 164,
which reciprocates with respect to cylinder liner 140. Seal 162 has
a gap and is installed in groove 149 of ring 144 before installing
in groove 145 in cylinder 140. Thus, when ring 144 is caused to
form a helix to enter the cylinder, seal 162 also forms a
helix.
[0046] Piston rings, which are designed for installation in a
groove in a piston, such as ring 106 in FIG. 1, are manufactured by
taking a flat wire and forming it into a helix. The diameter of the
helix is greater than the diameter of the ring as it is installed
in the piston so that there is spring force causing the ring to
press outwardly. A portion of the helix, less than 360.degree., is
severed to form each ring. Such a ring, when compressed to close
the gap, provides an outward pressure on the cylinder liner.
[0047] In the situation in which the ring is to be installed in a
stationary groove in the cylinder liner, the desire is to have a
ring that presses inwardly on the piston. A helix is formed that
has a diameter less than the diameter of the piston as it is
installed in the cylinder liner. The ring cut from the helix to be
installed in the groove in the cylinder liner extends over
360.degree., i.e., the ends overlap. The ring must be forced to
expand to enter the groove so that the ends no longer overlap.
[0048] A procedure by which the stationary rings can be installed
into the groove in the cylinder liner starts at 200 in FIG. 14. In
block 202, a deformable seal, possibly an elastomeric material, is
placed into the groove in the ring. Alternatively, a tension spring
is placed in the groove in the piston. In block 204, the sealing
ring is caused to form a helix or spiral with a diameter less than
the diameter of the cylinder. In block 206, the sealing ring is
slid into the cylinder. In block 208, the ring is caused to expand
in the groove in the cylinder. In one embodiment, the ring is
expanded by use of a fixture. The piston is slid into the cylinder
to engage with the sealing ring in block 210. In block 212, the
spacer ring is compressed so that the ends are proximate each
other. The spacer ring is placed in the cylinder and then expanded
into the groove in the cylinder in block 214.
[0049] In embodiments in which there is no groove in the sealing
ring and the neutral position of the sealing ring is such that
outer diameter of the sealing ring is less than the cylinder, the
procedure starts in 300 of FIG. 15. In block 302, the sealing ring
is placed on a fixture. In one embodiment, the bottom of the piston
is coupled to one end of the fixture. The sealing ring and fixture
are slid into the cylinder in block 304. In block 306, the fixture
is used to cause the ring to expand outwardly and to expand into
the groove in the cylinder. In the process, the ends of the rings
no longer overlap to form a helix. Instead the ends of the ring are
proximate each other and the ring lies in a plane. In block 308,
the piston is slid toward the sealing ring so that the sealing ring
encircles the piston (rather than the fixture). The spacer ring is
compressed so that the ends touch in block 312. The spacer ring is
slid into the cylinder and allowed, or forced, to expand into the
groove adjacent to the sealing ring 314.
[0050] Referring now to FIG. 16, a sealing ring 240 has a groove,
the bottom of which is shown by dashed circle 242. Sealing ring 240
has been formed into a helix by overlapping ends 244 and 246 (per
block 202 in FIG. 14). A tension spring 248 is placed in the
groove. But, the tension spring 248 bulges out in the region of
overlap. Returning now to FIG. 14, the result of block 204 appears
as shown in FIG. 16. In block 208, the sealing ring expands in the
groove in the cylinder such that it is no longer in a helix, but
instead lies in a plane. While this occurs, the tension spring
should pop fully into the groove in the cylinder with the bulge
being taken up. A fixture may be used to cause the ring to expand
as desired. The fixture may be used in block 214 to assist in
installing the piston into the cylinder. Ring 240 of FIG. 16 is
shown in a side, helical orientation in FIG. 17. Groove 242 is only
visible in the areas near the ends 244 and 246 of ring 240 because
tension spring 248 is in groove 242 over most of the circumference
of ring 240. In the area of the bulge, tension spring 248 is out of
the groove and bends downwardly from the upper portion of ring 240
on the left hand side of FIG. 17 to the lower portion of ring 240
on the right hand side. Tension spring 248 causes ring 240 to push
inwardly toward the piston to seal against the piston.
[0051] In an alternative embodiment, a deformable seal is placed in
groove 242 of ring 240. The deformable seal is sized so that it is
deformed upon assembly so that it causes the ring to be pushed
inwardly. The deformable seal is not formed in a continuous ring
but is instead a ring with a gap with the gap aligned with the gap
in the sealing ring or is a linear seal that is placed in the
groove in the sealing ring.
[0052] Referring now to FIG. 18, a slice of cylinder 400 that has a
groove 402 is shown with a piston 404 inserted therein. Piston 404
has two compression rings 406 near the top 408 of piston 404 (top
of piston refers to the end of the piston proximate the combustion
chamber, not the orientation in FIGS. 18-24). A first portion of a
fixture 410 is placed against piston 404. Sealing ring 412 is
placed over fixture 410. In one embodiment, ring 410 is shown in
its neutral position in FIG. 18, i.e., with no spring tension. In
FIG. 19, a second portion of a fixture 414 is used to press sealing
ring 412 onto first fixture portion 410 causing sealing ring 412 to
expand outwardly. Ring 412 presses inwardly due to spring tension.
Referring now to FIG. 20, second fixture portion 414 pushes down
even more on ring 412 to cause it to expand in such a manner that
it no longer assumes a helical configuration and pops into groove
402. Ring 412 has a slight gap, as small as reasonable considering
tolerances in cylinder 400. In FIG. 21, fixture 410 and piston 404
are moved upwardly so that ring 412 is slid off of fixture 410 and
onto piston 404. Ring 412 presses inwardly on piston 404. Ring 412
is prevented from moving upwardly because it is contained in groove
402. In FIG. 22, fixture 410 has been removed and a spacer ring 416
is compressed and placed in cylinder 400. As compressed, ring 416
has negligible gap 418. In FIG. 23, spacer ring 416 is placed below
the edge of groove 402 and caused to spring outwardly, thereby
forming a gap 420. In FIG. 24, piston 404 is moved upwardly such
that spacer ring 416 now encircles piston 404 and sealing ring 412
is now encircling piston 404 at a different location than the end
of piston 404, as shown in FIG. 23.
[0053] In an alternative embodiment, sealing ring 412 is provided
with a tension spring in a groove in the outer surface of ring 412.
The tension spring is caused to pop fully into the groove in
sealing ring 412 in between the orientations illustrated in FIGS.
19 and 20.
[0054] In FIG. 25, an alternative embodiment of a spacer ring 500
in which a tension spring 504 is shown. Only the ends of spacer
ring 500 are shown. Spacer ring 500 has a groove 502 on the outside
surface. Tension spring 504 is placed in groove 502. As described
above in regards to another embodiment of the spacer ring, a large
gap is formed between the ends of the spacer ring when it is
installed in the groove. In the embodiment in FIG. 25, the ring is
spiraled such that the ring lies in a single plane with the two
ends of the ring overlapping. A chamfer 506 is provided on one of
the ends of spacer ring 500 so that when unspiraling spacer ring
500, chamfer 506 allows the two ends to move past each other and
leave a shorter gap. Chamfer 506 can be slightly curved with the
curve designed so that a corner of the opposite end of the ring
strikes such a curve during installation. Additionally, groove 502
is cutback further in region 508 in an end of the ring. The cutback
allows the ring to assume a smoother profile during the
installation procedure. Without such a cutback, tension spring 504
would have a significant bend.
[0055] A view of the cylinder liner 520 with ports 522 is shown in
FIG. 26. A groove 528 provided in the cylinder liner has a sealing
ring 524 and a spacer ring 526 disposed therein. Both of rings 524
and 526 have an inner surface, i.e., the surface that wipes the
piston, with two ridges 530 and 532, respectively. Each of ring 524
and 526 have two grooves (not visible) into which tension springs
534 and 536 are installed. Multiple tension springs can be used to
provide more tension on the sealing and spacer rings.
[0056] While the best mode has been described in detail with
respect to particular embodiments, those familiar with the art will
recognize various alternative designs and embodiments within the
scope of the following claims. While various embodiments may have
been described as providing advantages or being preferred over
other embodiments with respect to one or more desired
characteristics, as one skilled in the art is aware, one or more
characteristics may be compromised to achieve desired system
attributes, which depend on the specific application and
implementation. These attributes include, but are not limited to:
cost, strength, durability, life cycle cost, marketability,
appearance, packaging, size, serviceability, weight,
manufacturability, ease of assembly, etc. The embodiments described
herein that are characterized as less desirable than other
embodiments or prior art implementations with respect to one or
more characteristics are not outside the scope of the disclosure
and may be desirable for particular applications.
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